Jeff, dual V1811s should be pretty @&$* impressive. I want to upgrade my sub (an SVS PB-12 Plus 2 that TV also designed) but I think I'd want to go sealed. The S3010 would probably be the winner. the volume of my room is about 3,800 CF, and I think it would be plenty to pressurize things.

I had my choice down to a single PSA S3811 or two V1811. Tom V. thought I needed the vented option with my room especially <35 Hz were the V models have 6 to 8 db more output. I took his advice. A bit more money but I want to do this once and done. However, I think I would be happy with either one. Also, more flexibility with two subs and you can stack them vertically or horizontally or space them out. Yes crown amps I have had the Krell's and CJ and all the other big bucks amplifiers. This humble crown gets within 90% of the best i have heard. They use Crowns new DriveCore technology. They have to be the best kept secret in home theater. Here is professional reviewer Andrew Robinson with a very positive review about them:http://www.hometheaterequipment.com/threads/1319-Crown-Audio-XLS-Drivecore-Series-Amplifier-The-OFFICIAL-Thread/page5

Thanks Jeff couldn't find it.
I would think one sub would be loud enough. 2 will have less distortion, same output both subs sharing half work less excursion and flexibility of moving around the room to smooth out the response of the room. Good luck on calibrating. Can be done but tricky with using 2. Reading the owners manual, it suggests playing bassy music and adjusting the delay using a sound pressure level meter, I think if you use this method you should use music with long sustained bass notes like organ. Also you can run log sweeps in an A-B loop on your disc player. Good luck and enjoy.
Don't forget to post your results and how you got there.

I use Audyssey XT32 as a subwoofer calibration device. It handles two subwoofers independently. The main task will be finding placement options. I really only have two choices. 1. Place each speaker next to the L/R mains. 2. Stack them vertically on the hard left wall. I do not have anywhere behind me and the right wall has a table already. Any thoughts would be welcomed. Tom says they will be shipping early to mid next week.

I didn't have luck with Audyssey, they have different powered algorithms, and the second AVR I had was very inexpensive. I did the setup manually.
Started with SPL meter using pink noise full bandwith to set volume. Then ran log sweeps from 100hz down to 10hz in an AB loop on the disc player. I adjusted the Q factor untill the lowest frequencies were the heaviest but not distorted. The crossover I adjusted from my seat using the variable adjustments inside the AVR. I did it in 10 db increments starting at 100hz down to 40hz. Turned out 80hz was the best match.
For a signal to do the crossover point for sub I used Transformers Dark of The Moon chapter 19 to the end. This movie has extreme low end effects.
I have a low priced sub an HSU VTF-3 MK4. It came with a test disc and contains a recording of Saint Saeans, pardon my spelling, organ music that was recorded in Boston. Dr. Shu says it's the finest recording he can find that contains a 16hz organ pedal note.
I always still had a limit on how loud I could play heavy music in my ROOM.
The room gain and RT60 decay rate interfered with an overload of pressure and if any louder the bass would get boomy. I have extremely flat response speakers, and am drving them with 500watts so plenty of head room. They are rated for max 375watts. My amp is super high current and has a great damping factor. The sub can blow out the windows but power isn't always the issue. The room could only take so much energy and it overloaded. I need to treat the room to get more volume without getting boomy. My pre-pro that replaced my AVR has a very strong algorithm, and after manually setting everything up I ran the room correction program and it made the system better than I could tune it in.
Even with terrible acoustics it squeezed more heaviness out at higher volume than I could get. Very humbling. I will send you a PDF file containing a lot of information on sub woofers. It helps to have as much information as you can get.